When interpeting the contents of images the detection of regions with homogeneity in characterizing features is an important step of the analysis. These regions are typically characterized in that one or several features within said regions are relatively constant or vary in a continuous and predictable way. Such continuously varying features may for instance be the curvature of lines and edges of an image. The feature could also be a matter of gradual shadings of the lighting of an image or the variation in the resolution of details as a function of the distance in a perspective image. Other characterizing features can also be detected.
On on-going problem has been that the characterizing of the variation is especially sensitive to noise. It has therefore been difficult to distinguish between low level noise in the image and characterizing features that show a stable variation. Attempts to overcome this problem have centered around efforts in areas relating to computerized image analysis and in particular to methods which have been implemented by means of a program for use with a general purpose computer. However, such methods have been inherently slow. The present invention concerns an apparatus by means of which with high speed and reliability it is possible to distinguish regions that have an even, continuous and predetermined variation of a feature from those regions that show an uneven, random variation.